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This article focuses on wear tests of spur gears made with the use of additive manufacturing techniques from thermoplastic materials. The following additive manufacturing techniques were employed in this study: Melted and Extruded Modelling (FDM) and Fused Filament Fabrication (FFF). The study analysed gears made from ABS M-30 (Acrylonitrile Butadiene Styrene), ULTEM 9085 (PEI Polyetherimide) and PEEK (Polyetheretherketone), and the selection of these materials reflects their hierarchy in terms of economical application and strength parameters. A test rig designed by the authors was used to determine the fatigue life of polymer gears. Gear trains were tested under load in order to measure wear in polymer gears manufactured using FDM and FFF techniques. In order to understand the mechanism behind gear wear, further tests were performed on a P40 coordinate measuring machine (CMM) and a TalyScan 150 scanning instrument. The results of the gear tests made under load allow us to conclude that PEEK is resistant to wear and gear train operating temperature. Its initial topography undergoes slight changes in comparison to ABS M-30 and Ultem 9085. The biggest wear was reported for gears made from Ultem 9085. The hardness of the material decreased due to the loaded gear train’s operating temperature.

Aiming at the starwheel loading mechanism of roadway tunneling equipment, the problems of coal returning and low loading efficiency are caused by the unknown matching mechanism between the profiled starwheel teeth number and the coal rock particle diameter. Through the 80 kinds of working condition planning simulations of the combination of profiled starwheel gear teeth number, rotational speed, and coal rock particle diameter, explore the relationship between the profiled wheel teeth number and coal rock particle diameter adaptability. Propose the evaluation criteria of profiled wheel teeth number adaptability composed of three indexes of loading quality, coal returning quality, and loading power. Reveal the change rule of the influence of the profiled wheel teeth number, rotational speed, and coal rock particle diameter on the evaluation indexes. The results show that when n = 50 rpm, profiled starwheels loaded with 30–50 mm coal rock dumped the minimum mass of coal, maximum loading mass when loading 30–50 mm coal rock with three- and four-tooth starwheels, 20–30 mm coal rock with five-tooth starwheels, 10–20 mm coal rock with six-tooth starwheels, and 5–10 mm coal rock with seven-tooth starwheels; negative correlation of dumped coal mass with starwheel speed and coal rock particle size; loading power increases with increasing starwheel speed and coal rock particle size. The research results provide a theoretical basis and data support for the selection of the number of teeth of the profiled wheel loading mechanism, the optimization of matching the nature of coal and rock, and the continuous and efficient operation.

Harmonic drives have high load capacity, kinematic accuracy, and small weight and dimensions' parameters, compared to other transmissions. Due to the variable stiffness in the areas of the teeth and tooth sockets, the toothed rim of the harmonic drive during bending takes the shape of a polyhedron. This effect most strongly appears when the gear ratio is less than 60. For this reason the geometric synthesis of harmonic drives with gear ratios of less than 60 is an important task. In this paper, the law of deformation of the flexible gear is given by harmonic oscillations of the inner angles of the polygon. The dependences which allow the teeth of a rigid gear to be profiled, taking into account the effect of the \"polyhedron\" of the toothed rim of the flexible gear are obtained. The proposed dependences are the basis of the geometric synthesis of harmonic drive elements.

The contact pattern between gear teeth is one of the most significant indicators of proper gear operation. This paper presents an analysis of the contact pattern of gears with a sinusoidal profile. The gear geometry was obtained through direct solid simulation of the machining process. Generally, analytical, numerical, and experimental methods are used for contact pattern analysis in gearboxes. This article presents contact pattern investigations using numerical methods and a novel experimental method that utilizes pressure measurement films. A proprietary program using image analysis was used for the contact pattern analysis. The numerical studies utilized the Finite Element Method (FEM) and the CAD method. The results obtained from the presented methods show good convergence.

The basic properties of gears must be considered: the shape of their gearing, their load capacity, and the meshing stiffness, which affects the noise and vibration. When designing large gears, it is important to choose the correct shape of the gear body. Large gears used in marine gearboxes must be designed with as little weight as possible. The requirements of sufficient stiffness of the gear wheel body, as well as the meshing stiffness, must be met. This paper is devoted to the influence of spur gear wheel body parameters on gearing deformation and meshing stiffness. The stiffness of the gear is solved on the basis of the deformation of the gearing teeth, which is determined by the finite element method. Examples of the simulation and subsequent processing of results demonstrates how the individual parameters of the gear wheel body influence the stiffness of the gearing teeth. At the same time, the results point to designs of suitable shape and dimensions to achieve the required stiffness of the gearing teeth, but with the lowest possible weight of the spur gear wheel body.

A hybrid strategy is proposed to meet the challenge of obtaining the profile of micro gear teeth with a small modulus. Firstly, the contact probe segmentally obtained the falling flank profiles with an auxiliary lifting mechanism to avoid interference when it climbs on the rising slope. Then, the noncontact chromatic confocal displacement sensor efficiently acquired the gear peak positions to carry out the two-point error separation with the gear peak positions from the probe measurement. Finally, actual experiments were carried out to obtain the profile of a harmonic drive flexspline. Compared with the commercial ultraprecise profiler, the proposed method provides measurement results with a deviation of less than 20 μm. In conclusion, the hybrid strategy is feasible and accurate for drawing the micro gear teeth profile without any collision between the measuring probes and the measured workpiece.

The progress of additive manufacturing technology brings about many new questions and challenges. Additive manufacturing technology allows for designing machine elements with smaller mass, but at the same time with the same stiffness and stress loading capacity. By using additive manufacturing it is possible to produce gears in the form of shell shape with infill inside. This study is carried out as an attempt to answer the question which type of infill, and with how much density, is optimal for a spur gear tooth to ensure the best stiffness and stress loading capacity. An analysis is performed using numerical finite element method. Two new infill structures are proposed: triangular infill with five different densities and topology infill designed according to the already known results for 2D cantilever topology optimization, known as Michell structures. The von Mises stress, displacements and bending stiffness are analyzed for full body gear tooth and for shell body gear tooth with above mentioned types of infill structure.

Low-angle straight tooth face gear transmission has significant advantages such as compact structure, small axial force, good shunt effect, and insensitivity to installation errors, demonstrating great superiority in the main reduction and torque distribution structure of helicopters. In this paper, the calculation of cutting force in the process of gear turning is studied, and the mathematical model of low-angle straight tooth face gear is established, and the numerical calculation and simulation analysis of cutting force are completed. On this basis, the gear machining test was completed on the gear machine, and the actual cutting force was collected, which verified the correctness of the cutting force calculation method and the feasibility of the cutting force optimization scheme, and provided a new solution for the cutting force calculation of the low-angle straight tooth face gear machining in industrial production.

This paper proposes a new testing method, phased array ultrasonic testing, for the internal defects of gear teeth, which can be used to inspect the teeth of final products, breaking the limitations of incomplete volume coverage of conventional ultrasonic testing. This paper mainly discusses the inspection process of phased array ultrasonic testing, and verifies the feasibility of phased array ultrasonic testing for gear teeth defects of finished products by using physical and chemical inspection technology. The practical application results show that the phased array ultrasonic testing technology uses sector scanning mode to scan the area comprehensively between the pitch circle and the base circle, and the inspection image displayed by the equipment is intuitive, which can clearly identify defects. The number of defects inspected by phased array ultrasonic testing is consistent with the results of the physical and chemical inspection technology. The above summary shows that phased array ultrasonic testing is feasible, and the test results are reliable.

This article studies the calculation method for the tooth root bending stress of a high-tooth gear pair with a high contact ratio. The boundary point of the double-tooth meshing zone of the high-tooth gear pair is used as the loading point for the load, and the calculation formula for the bending stress at the dangerous section of the tooth root is obtained. By using ANSYS finite element simulation, the effect of the addendum coefficient, pressure angle, and other gear parameters on the bending stress of the tooth root is studied. The analysis shows that increasing the pressure angle will reduce the bending strength of the tooth root. Increasing the coefficient of a tooth’s top height will lead to an increase in the bending strength of the tooth root. Comparing the finite element analysis (FEA) results with the theoretical calculation results, the analysis shows that under low loads, the maximum error of the theoretical calculation values of the driving toothed gear and driven gear shall not exceed 13.53% and 15.42%, respectively. Under high loads, the maximum theoretical errors of the driving toothed gear and driven gear shall not exceed 8.78% and 10.91%, respectively. This verifies the correctness of the calculation method, which is of great significance for improving the load-bearing capacity of high-tooth gears and for guiding tooth shape design.